It is estimated that approximately 250,000-300,000 people experience cardiopulmonary arrest (CPA) each year in the United States. Approximately 80% of resuscitated patients remain in a coma for some time. Despite modern day healthcare efforts, many of these patients will not awaken. In such cases, caregivers are confronted with the difficult choice of continuing aggressive therapy or withdrawing life support. In evaluating the overall clinical picture of these comatose patients, Evoked Potentials (EP) may provide useful adjunct feedback on brain function. Thus we propose a Phase I effort to develop quantitative EP (qEP) analysis techniques for evaluation of comatose patients. Specifically, we propose Mutual Synchronicity (MS) as a method to combine aspects of amplitude and latency analysis into a unifying measure of brain injury. The goals of our Phase I study are 1) to develop Mutual Synchronicity (MS) based on advanced signal processing theory for objectively characterizing cortical and brainstem electrical activity, and 2) to test MS in a preliminary evaluation of comatose patients during post-CPA recovery. In the long-term, we plan to investigate the use of this technology as a bedside tool for monitoring the progression of coma after CPA.